1. Field of the Invention
The invention relates to a communication system, ports of a communication system and a method for managing a communication system. In one preferred embodiment, the invention relates to a synchronous communication system formed as a ring network of two or more communication ports coupled in daisy chain fashion to one another to allow communication.
2. Description of the Related Art
The following descriptions and examples are given as background only.
A communication system is generally known as a system that permits communication between nodes interconnected by a transmission line. Each node can transmit and receive information across the transmission line. A communication system of interconnected nodes can be organized in various topologies, such as a bus, ring, star, or tree topology or a combination thereof.
A bus topology network is generally regarded as linear. Transmissions from one node propagate along the transmission line and are received by all other nodes connected to that bus. A ring topology network, however, generally consists of a series of nodes connected to one another by unidirectional transmission links to form a single, closed loop. Examples of a ring network are described in IEEE 802.5 and Fiber Distributed Data Interface (FDDI).
The transmission line between nodes can be either wired (for example, copper wire, fiber optic, etc.) or a wireless transmission medium may be chosen for the transmission line, respectively.
For real-time applications, or for transferring synchronous streaming data, it is desirable for the communication system to have a low latency and a low transmission overhead. In addition, it is often necessary to synchronize clocks between nodes and to further provide a time reference for all nodes in the communication system.
U.S. Pat. No. 5,907,685 discloses a method of time synchronization between network nodes based on extensive bidirectional communication. The bidirectional communication disclosed in U.S. Pat. No. 5,907,685 causes a significant load on the network, when done regularly in short intervals. Furthermore, there is significant computing power required to evaluate the communicated data. For timing synchronization, a lead computer distributes the timing information to other nodes in the network. For this purpose, the role of lead computer must be assigned to a specific computer in the network. In most networks, computers are often attached to or removed from the network. When this occurs in the communication system disclosed in U.S. Pat. No. 5,907,685, it may be possible that two or even more computers are assigned the role of lead computer for distributing timing information. No method is disclosed in U.S. Pat. No. 5,907,685 for identifying multiple lead computers in the network.